In Vitro Cytotoxicity of Some Natural and Semi-Synthetic Isocoumarins from Paepalanthus bromelioides

Abstract

Numerous natural compounds have a potential for therapeutic applications, but may have to be chemically modified to alter toxic side effects. We investigated structural parameters that could affect the cytotoxicity of isocoumarins similar to 9,10-dihydroxy-5,7-dimethoxy- 1H-naphtho(2,3c)pyran-1-one (paepalantine 1). Paepalantine 1 has antimicrobial activity, as well as significant in vitro cytotoxic effects in the McCoy cell line. Two other natural and two semi-synthetic isocoumarins with similar structures obtained from the capitula of Paepalanthus bromelioides were tested on the same cell line by the neutral red assay. Substitution of the 9 and/or 10-OH group made these compounds less cytotoxic.

Inhibition of Nitric Oxide and Tumour Necrosis Factor-α Production in Peritoneal Macrophages by <i>Aspergillus nidulans</i> Melanin

“…The probable mechanism involved is the modulation of signal transduction pathways since pre-treatment with this pigment reversed the A wide variety of natural products are claimed to possess immunomodulatory activity, but it is often difficult to differentiate this activity away from their associated cytotoxicity. 51) In view of a potential practical application of the melanin from A. nidulans as anti-inflammatory agent, it was important to evaluate the toxicity of this pigment.…”

Alkylated Isocoumarins fromPituranthos Scoparius

“…Despite their relative scarcity and probably because of their easy access through total synthesis, they are increasingly investigated for their biological properties which include -secretase inhibition [16] and cytotoxicity [17]. New biological properties of the isocoumarins and other metabolites from P. scoparius are currently being investigated.…”

Naphthopyranones – isolation, bioactivity, biosynthesis and synthesis

“…19 Thus, upon acetylation of 8 a diacetate was formed and shown to be identical with the diacetate of toralactone 1, indicating migration of the doublebond takes place under these conditions. 27 A number of the glycosides of paepalantine have also been assessed for cytotoxic 28 and mutagenic 29 activity. Both isotoralactone 8 and toralactone 1 display antimicrobial activity against Staphylococcus aureus (MIC 2-3 mg mL À1 ) and Escherichia coli (MIC 6-12 mg mL À1 ) 7 and show only moderate inhibitory activity towards cAMP phosphodiesterase.…”